After a strong start to the morning's trade, things don't look so upbeat for the S&P/ASX 200 Index (ASX: XJO) this afternoon. At the time of writing, the ASX 200 has given up most of its early lead today, and is sitting pretty much flat at 8,226 points. But let's talk about one ASX 200 healthcare stock that is plunging in value.
That ASX 200 healthcare stock is none other than Neuren Pharmaceuticals Ltd (ASX: NEU).
Yesterday, Neuren shares closed at a flat $12 each. This morning, those same shares opened at $12.03 but quickly started dropping. At the time of writing, the ASX 200 healthcare stock has lost a horrid 8.83% and is down to just $10.94 a share. That's after going as low as $10.90 this afternoon.
So what on earth is going on here that has seen Neuren lose close to 10% of its value in just a single trading day?
Well, it appears that this steep sell-off is a consequence of an ASX announcement Neuren made to investors this morning just before market open.
Neuren shares plunge amid big Europe news
This announcement revealed that Neuren's partner, Acadia Pharmaceuticals, has submitted a marketing authorization application to the European Medicines Agency for its trofinetide treatment. Trofinetide is a therapeutic treatment for Rett syndrome in adults and pediatric patients two years and older.
Acadia Pharmaceuticals reportedly expects approval for trofinetide to occur in the first quarter of 2026. If it does indeed gain approval from the relevant agencies, it will be the "first and only approved therapy for Rett syndrome in the European Union".
Trofinetide is already an approved treatment for Rett syndrome in the United States and Canada under the 'Daybue' trademark.
If approved, Acadia will sell trofinetide in Europe under license from Neuren. Upon the first commercial sale of the treatment in Europe, Neuren is contracted to receive a US$35 million payment from Acadia. That's in addition to ongoing royalty payments.
Why has this ASX 200 healthcare stock taken a dive?
It's not entirely clear why investors have reacted so poorly to this news out of Neuren today. The rollout of trofinetide in Europe has been anticipated for some time.
Perhaps investors were expecting a quicker European rollout or an announcement regarding other planned rollouts in Japan and other countries.
Regardless, it's a rough day for this ASX 200 healthcare stock. It's also some fresh salt in the wounds of Neuren's investors.
After today's share price plunge, this ASX 200 healthcare stock is down a painful 53.6% over the past 12 months. Investors will no doubt hope for a turnaround over the rest of 2025.
